EP2751475A1

EP2751475A1 - Optical device, in particular for a motor vehicle

Info

Publication number: EP2751475A1
Application number: EP12756168.6A
Authority: EP
Inventors: Pierre Albou
Original assignee: Valeo Vision SAS
Current assignee: Valeo Vision SAS
Priority date: 2011-09-02
Filing date: 2012-09-03
Publication date: 2014-07-09
Also published as: WO2013030396A1; FR2979593B1; US9677734B2; CN103782085B; CN103782085A; US20140301100A1; FR2979593A1

Abstract

The invention relates to an optical device (1) for a motor vehicle, in particular a motor vehicle lighting and/or signalling device, comprising a surface light source (3). The device is characterised in that it includes a member (2) for shaping a light beam, said member deflecting first light rays (202, 203) of the beam emitted by a face of the surface light source, but not deflecting second light rays (201) of the beam emitted by the same face of the surface light source.

Description

Optical device, in particular for a motor vehicle

The present invention relates to an optical device, in particular for a motor vehicle, such as a lighting and / or signaling and / or interior lighting device having in particular a photometric function useful for the road circulation of the vehicle, enabling the vehicle to be seen by other vehicles or the driver of said vehicle to see outside.

In the field of signaling, as in that of lighting, many regulatory constraints leave little room to change the appearance of lights in the lit state, since the photometry of light beams is imposed to a very large extent . However, the style and aesthetics are very important data for this type of product, and the automotive suppliers seek to give a "signature" to their products, so that they are easily identifiable by the end user.

It is known to use surface light sources to perform lighting and / or signaling and / or interior lighting functions for motor vehicles. A new type of surface light source is currently developing that are organic light emitting diodes. It would be interesting to use them to perform lighting and / or signaling functions. However, these sources have disadvantages. The directivity levels attained today are of the form (cos θ) ¹¹ , Θ representing the emission angle with respect to the normal at the emission surface and (cos Θ) ¹¹ representing the intensity level of the light emitted in the direction Θ relative to the intensity emitted in the direction of the normal to the surface. Such a level of directivity is insufficient to effectively perform certain signaling functions, including a braking signaling function. Indeed, to achieve such a signaling function, it is necessary to have a higher directivity in the vertical plane, that is to say that it is necessary that the light emitted by the diode is less diffused vertically.

To remedy this drawback, organic light-emitting diodes having a layer on their emitting surface which makes it possible to modify their directivity are known. Is achieved and a directivity of the form (cos θ) ^15, Θ representing the angle of emission with respect to the normal to the emission surface and (cos Θ) ¹⁵ representing the level of illumination in the direction Θ. Contrary to what has been seen previously, with such a solution is reached a directivity too high in the horizontal plane to achieve a braking type of signaling function.

Considering a rectangular organic electroluminescent diode having an emitting surface of 5 mm by 220 mm arranged perpendicularly to an optical axis and having a global emission indicator in cos ¹¹ of the angle of observation relative to its normal. We then obtain the infinite distribution shown in Figure 1 (for an arbitrary flux of 50lm). The horizontal and vertical sections are identical and have a varying profile as cosine ¹¹ . One of these sections is shown in FIG. 2. With such a system, the photometric grid shown in FIG. This photometric grid does not conform to the standardized photometric grid for a braking type signaling device. Indeed, the light intensity emitted in particular in the vicinity of the optical axis is insufficient while much light is emitted unnecessarily above 15 ° upwards and below 15 ° downwards.

Moreover, the luminances produced by organic light-emitting diodes are limited. It is therefore necessary to provide extended emission areas to perform a lighting function and / or signaling. The object of the invention is to provide an optical device overcoming the disadvantages mentioned above and improving the optical devices known from the prior art. In particular, the invention proposes a simple and inexpensive optical device making it possible to use organic light-emitting diodes of limited dimensions to carry out lighting and / or signaling and / or interior lighting functions of a motor vehicle. According to the invention, an optical device of a motor vehicle, in particular a lighting and / or signaling and / or interior lighting device for a motor vehicle, comprises a surface light source and a setting member. shape of a light beam deviating from the first light rays of the beam emitted by a face of the surface light source, this member not deviating from the second light rays of the beam emitted by this same face of the surface light source.

The emission area of the surface light source may be greater than 1 cm ² , or even greater than 5 cm ² , or even greater than 10 cm ² .

The surface source of light may comprise an organic light-emitting diode.

The optical device may comprise a housing closed by a closure glass inside which are the surface source of light and the shaping member.

The shaping member can be made by a transparent monoblock piece.

The shaping member may comprise a deflection member deviating primarily from the reflection rays. The deflection element may comprise a first reflection element, in particular a first plane reflection element, and a second reflection element, notably a second parabolic section reflection element whose focus is at the center image level. of the face by the first reflection element or substantially at the image of the center of the face by the first reflection element.

The shaping member may comprise a deflection member deviating primarily from the refractive rays.

The deflection member may comprise an upper portion and a lower portion, the lower and upper portions being joined by a mechanical connecting member.

The first and second rays can pass through the shaping member.

Another object of the invention is a motor vehicle comprising an optical device defined above.

The appended drawing shows, by way of example, various embodiments of a lighting and / or signaling device for a motor vehicle according to the invention.

FIG. 1 is a diagram representing the infinite illumination distribution of a surface organic diode-type light source, the various substantially concentric curves representing illumination levels. FIG. 2 is a diagram showing the change in intensity of illumination according to the angle formed between the normal to a surface emitting surface of a surface-emitting diode and the direction of emission. Figure 3 is a front view of a first embodiment of an optical device according to the invention.

Figure 4 is a perspective view of the first embodiment of the optical device according to the invention.

Figure 5 is a sectional view along a vertical plane of the first embodiment of the optical device according to the invention.

FIG. 6 is a diagram representing the distribution of illumination at infinity emitted by an optical device according to the invention.

FIG. 7 is a diagram representing the evolution of the intensity of the illumination according to the angle formed between the normal to the optical axis of the optical device according to the invention and the direction of emission at the output of the optical device according to the invention for rays emitted in a horizontal plane containing the optical axis of the invention.

FIG. 8 is a diagram representing the distribution of illumination at infinity emitted by a portion of the light beam coming from an optical device according to the invention.

FIG. 9 is a diagram representing the evolution of the intensity of the illumination according to the angle formed between the optical axis of the optical device according to the invention and the direction of emission at the output of the optical device according to the invention. for rays emitted in a vertical plane containing the optical axis of the invention. FIG. 10 represents a standardized photometric grid of brake signaling light and the luminous intensity values obtained in this grid for an emitted luminous flux of 21 μm with an optical device according to the invention.

FIG. 11 represents a standardized photometric grid of stop signaling light and the luminous intensity values obtained in this grid for an emitted luminous flux of 21 μm using an organic light-emitting diode without optics for shaping its emitted beam.

FIG. 12 represents the lit appearance of an optical device according to the invention, seen from the optical axis of the device.

FIG. 13 represents the lit appearance of a device according to the invention, seen at an angle of 10 ° with the optical axis in the horizontal plane.

FIG. 14 represents the lit appearance of a device according to the invention, seen at an angle of 10 ° with the optical axis in the vertical plane.

Figure 15 is a perspective view of a second embodiment of the optical device according to the invention. Figure 16 is a sectional view along a vertical plane of the second embodiment of the optical device according to the invention.

Figures 17 and 18 show the illuminated appearance of an optical device according to the second embodiment, seen from the optical axis of the device. Figure 19 is a sectional view along a vertical plane of a third embodiment of the optical device according to the invention.

A first embodiment is described below with reference to FIGS. 2 to 5. The optical device 1 is a lighting and / or signaling device for a motor vehicle, in particular a braking signaling device. The device comprises a surface source of light 3, a device 2 for shaping a light beam deviating from the first light rays 202, 203 of the beam emitted by a face 31 of the surface light source, this member not deviating from the light sources. second light rays 201 of the beam emitted by this same face 31 of the surface light source.

The surface source of light is rectangular and elongated. For example, it is about 220 mm long and about 5 mm high. The source is intended to be mounted so that it extends horizontally, its light-emitting face 31 being oriented vertically. The optical axis 90 of the optical device is perpendicular to this face 31. It intercepts the source in the middle of the height of the face, preferably in the center of the face F.

The forming member 2 is made of transparent material such as polymethyl methacrylate (PMMA). It is for example obtained by extrusion or molding. The shaping member extends parallel to the length of the source. For example, the section of the shaper remains constant over the entire length of the source. Alternatively, the section could evolve to create style effects.

The shaping member comprises an upper portion 41, a central portion 42 (half shown) and a lower portion (not shown). The lower part is for example symmetrical to the upper part relative to the horizontal plane passing through the optical axis.

The upper part 41 constitutes a first assembly allowing radii emitted by the source to exit at an output face 25 of the first set in a direction substantially parallel to the optical axis 90.

The lower part 43 constitutes a second assembly allowing rays emitted by the source to exit at a second output face of the second set in a direction substantially parallel to the optical axis 90.

The central part 42 has the function of mechanically connecting the upper part and the lower part. It is also made of transparent material so that rays emitted by the source can pass through it. This crossing is performed without deviation (or significant deviation) light rays emitted by the source. Thus, thanks to the device for shaping the beam, at the output of the optical device light emission is obtained in three bands 101, 102 and 103, as shown in FIG. 12. Moreover, one obtains, with such an optical device whose light source emits a luminous flux of 21 μm, the photometric grid shown in FIG. 10. It is therefore possible to produce a braking signaling device with an organic light-emitting diode type light source having the dimensions mentioned above. above.

The first light rays 202, 203 emitted by the source form in the plane P a sufficiently large angle with the optical axis not to pass through the central portion 42 of the shaping member. This plane P is preferably a vertical plane normal to the face 31 of the light source. Thus, these first light rays are emitted towards the upper part (or the lower part), enter it at a surface 26 and are guided by it as described below. Once in the upper part, a first reflection element 22, for example constituted by a face 22 of the shaping member, deflects reflection by rays. This reflection is for example carried out because of a total reflection at a diopter, the refractive index of the upper part being greater than that of the environment in which it is located. Alternatively, the face 22 may be treated, for example metallized. Once reflected, the first rays are again reflected by a second reflection element 24, for example constituted by a second surface 24. This reflection is for example achieved because of a total reflection at a diopter, the refractive index of the upper part being greater than that of the environment in which it is located. Alternatively, the surface 24 can be treated, for example metallized. A surface 23 makes it possible to connect the surface 26 to the second reflection element 24.

The first reflection element 22 is preferably plane and the second reflection element is, for example, cylindrical with a parabolic section, the focus F 'of the parabola being at the level of the image of the center F of the face 31 by the first element of reflection 22.

Once reflected, the first spokes are again possibly deflected by the crossing of a diopter at the outlet surface 25 of the guide. Indeed, this face can form an angle δ with the vertical plane.

The second light rays 201 emitted by the source form in the plane P a sufficiently small angle with the optical axis to pass through the central portion 42 of the shaping member. Thus, these second light rays are emitted out of the shaping member at the level of the central part. To do this, the second light rays pass through a first dioptre 28 when they enter the shaping member, then pass through a second dioptre 27 when they exit the shaping member. They therefore leave the shaping member at a face 21 formed by the second dioptre 27.

The three strips 101, 102 and 103 are in fact made by the light rays issuing from the faces 21, 25 and from another non-represented face of the lower part of the shaping member. Given the geometry of the shaping member, it is noted that when deviating from 10 ° of the optical axis in a horizontal plane, all bands remain visible. On the other hand, when one deviates from 10 ° of the optical axis in a vertical plane, the bands disappear. Indeed, as illustrated in FIGS. 6 to 9, the shaping member makes it possible to "straighten" the light rays emitted from the face 31 by forming an important angle with the optical axis in the vertical plane P. that is, this angle is reduced at the output of the shaping member. On the other hand, the direction of the light rays, emitted by the face 31 forming a large angle with the optical axis in the horizontal plane, is not corrected.

For the overall beam from the optical device, we obtain the distribution at infinity shown in Figure 6. A horizontal section of this distribution is shown in Figure 7. For the upper band 102 from the optical device, we obtain the distribution at infinity shown in Figure 8. A vertical section of this distribution is shown in Figure 9.

In the first embodiment of the optical device, the shaping member is for example made in an extruded part of a length greater than or equal to that of the source (220mm in the example), whose cross section is constructed as follows: The cross-section of the central portion is a ring portion with an inner radius r1 such that 2 * r1 is greater than, and preferably adjacent (to minimize system bulk) the height of the source (for example, a source height of 5 mm, it is possible to take r1 = 3.5 mm) and with an external radius r2 as small as possible while remaining compatible with the manufacture of the shaping member and / or with its mechanical connection function. the upper part at the lower part (for example r2-r1 = 2.5 mm).

An angle a between a line D passing through the upper edge of the organic light emitting diode and the optical axis defines the vertical half-opening of the field in which the source is fully visible in the central band. The rays seen in this field are not deflected by the shaping member. For example, a = 5 °.

An angle β between the line D and the normal to the first reflection element 22 is greater than or equal to (and preferably equal to, minimize the bulk of the shaping member) the total angle of reflection in the material of the shaping member (for PMMA we have = asin (1/1 .49) ie β = 42.2 °). Under these conditions, all the rays coming from the source reaching the first reflection means 22 undergo a total reflection.

An angle γ beyond which, taking into account the directivity of the source, it is considered that we can neglect the light emitted, that is to say as

is negligible in front of 1.

In the example, with k = 1 1 and γ = 37 °, the above ratio is 0.067. F 'is the symmetrical of F with respect to the plane of the face 22.

M is the intersection of the internal reflection of the limit radius of angle a (emitted along line D) and of the line parallel to the optical axis and passing through the upper end of face 22 (end determined by the radius angle limit γ).

Finally, since the image of the source by reflection on the plane 22 is inclined with respect to the optical axis of the system, the maximum intensity of the beam created by the upper parabolic section is not necessarily located on the horizontal axis : A prism angle δ angularly shifts the beam from the upper band (eg δ = 6 °).

Depending on the value of the parameters chosen, the reflection on the parabolic section may be a total internal reflection for all the rays (this is the case in the example studied). In cases where it would not be, the face 24 can be metallized. The yield can then be very slightly decreased.

A second embodiment is described below with reference to FIGS. 15 to 18. This second embodiment of the optical device Y differs from the first embodiment described above in that the surface 23 making it possible to connect the surface 26 to the second element reflection 24 (and not playing optical role) is modified so as to create the surfaces 231 and 232. The goal is to implement a diffusing surface to create a light background between the strips 101, 102 and 103. For This requires that certain light rays emerge from the shaping member at the surfaces 22. In order for this effect to be significant (or even simply visible), it is necessary to give this diffusing surface 232 a suitable shape enabling intercept the rays emitted with an angle greater than the angle y, but close to this angle (beyond 47 °, one does not collects more, in our example, only 1% of the luminous flux). Such rays are reflected on the diffusing surface 232 before exiting the shaping member at the surfaces 22. This allows, as shown in FIGS. 17 and 18, to obtain, between the strips 101 and 102 and or between the bands 101 and 103, zones 104 of light emission of low intensity.

A third embodiment is described hereinafter with reference to FIG. 19. This third embodiment of optical device 1 "differs from the first embodiment described above in that, in the upper parts 41" and lower, the radii light are deflected by refraction and not by reflection. To do this, the upper and lower portions comprise dioptres 251, 252, 253 and 254. These dioptres are for example cylinders whose sections are portions of oval Descartes. The central portion 42 "may be identical to that described in the first embodiment.

The first light rays 302, 303 emitted by the source form in the plane P a sufficiently large angle with the optical axis so as not to pass through the central portion 42 "of the shaping member. transmitted to the upper portion 41 "(or the lower part) and enter it at a surface 28. The first rays are then deflected during the crossing of the diopters. For example, the radius 302 enters the upper part at the level of the face 28 without being deflected and leaves the upper part at the diopter 251 being deflected by it. Similarly, the spoke 303 enters the upper part at the level of the face 28 without being deflected and leaves the upper part at the diopter 252 being deflected by it. The second light rays 301 emitted by the source form in the plane P a sufficiently small angle with the optical axis to cross the central portion 42 of the shaping member. Thus, these second light rays are emitted out of the shaping member at the central part 42 ".This means that the second light rays pass through a first dioptre 28 when they enter the placing member. form, then pass through a second dioptre 27 when they exit the shaping member, and thus leave the shaping member at a face 21 formed by the second dioptre 27.

Of course, with this third embodiment, three bands of light are not observed, but in the example shown assuming that the lower part is symmetrical to the upper part.

These various embodiments may, unless technical incompatibility, be combined.

In the various embodiments, the second light rays are the rays emitted, in projection on the plane P, in the sector delimited by the line D, its symmetry with respect to the optical axis and the source and the rays whose extensions Intercept the line D or its symmetry only beyond the diopter 27. The projections of the first light rays on the plane P, in the sector, intercept the line D or its symmetry with respect to the optical axis intercept the line D or its symmetry before the dioptre 27.

In the various embodiments, the optical device comprises a housing 91 closed by a closure glass 92 inside which are the surface light source and the shaping member.

The shaping member is made by a transparent monobloc piece.

The first and second rays pass through the shaping member. It is considered that the second spokes passing through the central portion of the shaping member are not deflected by the shaping member. In the embodiments described, this is only true for light rays emitted from the longitudinal axis of face 31. Indeed, a light ray emitted from the upper edge of the face 31 parallel to the optical axis is slightly deflected during the crossing of the first dioptre 28, then again slightly deviated during the crossing of the second dioptre 27.

Preferably, in this document, it is considered that a radius is not deflected by the shaping member if its projection in the plane P is not deviated by it by more than 5 °. As a corollary, it is considered that a light beam is deflected only if its projection in the plane P is deflected by more than 5 °.

In the different embodiments, the optical device is a lighting and / or signaling device comprising a housing 91 closed by a closure glass 92. The optical device also has an optical axis 90.

In the different embodiments, the emission area of the surface light source is preferably greater than 1 cm ² , or even greater than 5 cm ² , or even greater than 10 cm ² .

In the various embodiments, the device has positioning elements and source retention relative to the shaping member. The device described above has a constant section over its entire length. However, one can imagine that the geometry of its section evolves along the device. Moreover, one can imagine that the device is not straight as shown in the figures but that it has at least one curvature.

The light source may include a plurality of light-emitting surface elements, including a plurality of organic light-emitting diodes. The organic light emitting diode may be of the conformable type. For example, it can be made by a film that can be deposited on a surface, especially on a left surface. Alternatively, it can be performed using a printing technique of the various layers, in particular by a printing technique on a left surface.

Such an organic electroluminescent diode device 60 is shown in FIG. 20. The device comprises an organic light-emitting diode 62 and an electrical voltage generator 61. The organic light-emitting diode comprises several layers: a cathode 63, an anode 65 and an organic layer 64. When the organic layer is subjected to an electrical voltage, it emits light radiation 66 propagating through the anode 65 which is transparent. relative to this radiation. The organic layer may optionally comprise different layers 641 to 645 of different organic materials. Preferably, organic light-emitting diodes comprising additional layers are used. In addition to the light-emitting stratum 643, the organic layer comprises a stratum 641 promoting the transport of electrons to the stratum 643 and a stratum 645 promoting the transport of the holes to the stratum 643. The organic layer can also include a stratum 642 blocking the holes from the lower strata 643 to 645 and a stratum 644 blocking the electrons from the upper strata 641 to 643. All of these strata constitute a microcavity whose thickness is adjusted to create an optical resonance . Thus, selective interferential reflectors are made which constitute resonant cavities. For example, an organic light-emitting diode of the type described in document FR 2 926 677 may be used. The optical device according to the invention makes it possible, for example, to perform one of the following functions: vehicle position signaling, direction change signaling, reversing signaling, braking signaling, signaling in the event of fog.

When the optical device is off, that is to say when the surface source does not emit light, an observer sees, when looking from the front of the device, the light source as if it were on each of the faces 21 and 25 or 251 to 254. In the case of an organic electroluminescent diode, the faces 21 and 25 or 251 to 254 thus have a metallic appearance.

Claims

claims

1. Optical device (1; 1 '; 1 ") of a motor vehicle, in particular a lighting and / or signaling and / or interior lighting device for a motor vehicle, comprising a surface light source (3) characterized in that the device comprises a shaping member (2; 2 '; 2 ") of a light beam deviating from first light rays (202,203; 302,303) of the beam emitted by a face of the light. surface source of light, this member not deviating from the second light rays (201; 301) of the beam emitted by this same face of the surface light source.

2. Device according to the preceding claim, characterized in that the emission area of the surface light source is greater than 1 cm ² , or even greater than 5 cm ² , or even greater than 10 cm ² .

3. Device according to one of the preceding claims, characterized in that the surface source of light comprises an organic light emitting diode (3).

4. Device according to one of the preceding claims, characterized in that the optical device comprises a housing (91) closed by a closure glass (92) inside which are the surface source of light and the body of formatting.

5. Device according to one of the preceding claims, characterized in that the shaping member is formed by a transparent one-piece piece.

6. Device according to one of the preceding claims, characterized in that the shaping member comprises a deflection element (22, 24) deviating mainly reflection rays. Device according to the preceding claim, characterized in that the deflection element (22, 24) comprises a first reflection element, in particular a first plane reflection element, and a second reflection element, in particular a second sectional reflection element. parabolic whose focus is at the image of the center of the face by the first reflection element or substantially at the image of the center of the face by the first reflection element.

Device according to one of Claims 1 to 7, characterized in that the shaping member comprises a deflection element (251, 252, 253, 254) which mainly deflects the refraction rays.

Device according to one of the preceding claims, characterized in that the deflection element (22, 24; 251, 252, 253, 254) comprises an upper part and a lower part, the lower and upper parts being connected by an element mechanical connection (21). 10. Device according to one of the preceding claims, characterized in that the first and second radii pass through the shaping member.